Seasonality in the early Holocene climate of Northwest Sudan: interpretation of Etheria elliptica shell isotopic data

The oxygen isotope ratios in the incremental growth layers in the shells of Etheria elliptica constitute a proxy record of rainfall patterns, and thus a record of seasonality. Analyses of shells of early Holocene age (6800 14C years BP or 5600 BC) collected from the lower reaches of Wadi Howar, near the confluence of that now-extinct river with the Nile, show an annual pattern of two rainy seasons in the present-day hyperarid southeastern Sahara, similar to that which prevails today in much of East Africa.